Air traffic management (ATM) system analysts simulate and model flights traveling through a region of airspace to analyze how future improved concepts support new capacity and efficiency improvements while maintaining or improving existing safety standards. A typical airspace study analyzes a schedule of multiple flights and determines the route and altitude each aircraft will fly.
Schedules of flights may be found in the Official Airline Guide (OAG). The OAG defines the aircraft type (such as Boeing 737, Airbus A320, and the like) as well as the departure and arrival times for thousands of flights world-wide every day. However, the OAG does not contain any information about the route or the altitudes of the flights. Therefore, four-dimensional (4-D) (x, y, z, time) trajectory flight path data must be supplied by the airspace simulation, based upon a number of factors, including the aircraft's cruise altitude capability and winds aloft, airspace restrictions and constraints, and the like.
Currently, there are no methods for planning the distribution of flights and cruise altitudes in the oceanic and remote airspace regions to optimize operations for all operators. Large numbers of aircraft fly across the oceans of the world. For example, over 1200 flights travel across the North Atlantic airspace every day. The planning task is made more difficult because of large separations between aircraft due to lack of radar or VHF voice communication coverage in these areas. HF voice communication or satellite-based communications are used in these regions for controller to pilot communications. However, aircraft are separated in these remote regions by larger lateral and longitudinal distances than if radar and VHF voice communications were available.
Thus, for several reasons, it would be desirable to provide collaborative methods for modeling and planning flight routes and altitudes in the oceanic and remote airspace. As a first example, in current air traffic control (ATC) practice, controllers handle aircraft one-by-one, on a “first-come, first-served” basis. The first airplane to enter the airspace is given the best available position regardless of the needs of individual operators, thereby affecting all following aircraft. A typical effect is that an aircraft capable of a faster cruise speed may follow a slower aircraft at the same cruise altitude. The faster aircraft must slow down or be vectored until there is enough space to allow the faster aircraft to safely pass the slower aircraft. Increasing use of slower regional jets and small business jets (that generally may have cruise speeds less than Mach 0.8, typically Mach 0.77 or less) demonstrates the limitations of the first-come, first served policy.
Another limitation of a first-come, first-served methodology manifests itself in inefficient flight routings (whether due to extended routes or inefficient flight altitudes). The air traffic controller is responsible for safely separating aircraft in a given three-dimensional volume of airspace called a “sector”. Controllers in adjacent sectors communicate with each other (currently using primarily a land-line phone) when an aircraft is about to enter another controller's airspace.
Currently, attempts are made to coordinate the movements of large numbers of aircraft through functions called flow and traffic management. However, flow and traffic management functions do not ensure that an aircraft will not be given an inefficient flight route. This is primarily because the ultimate responsibility for safe separation of aircraft resides with the controller responsible for a given sector. Thus, even if flow and traffic management functions have identified plans and constraints for a group of aircraft, variations in near-term operational parameters (such as changes to forecast/current weather, flight winds aloft differences from predicted, operational changes, or equipment failures) can result in the sector controller imposing additional restrictions on a flight if it is necessary to achieve safe separation distances between aircraft.
For example, in a typical case the flow and traffic management functions may have identified (through agreed-upon standard operating procedures or daily plans) aircraft separation distances. The controllers responsible for separating traffic at the typical cruise altitudes build in a gap or “slot” for the aircraft climbing up to cruise altitudes. However, one of the aircraft (aircraft A) may be late departing the airport due to ground congestion on one of the taxiways. Therefore, aircraft A will not fit into the gap available in the traffic flow. The controller responsible for this aircraft must find a way to safely separate aircraft A from the rest of the aircraft in the sector. The controller may let aircraft A cruise at a lower flight altitude until a gap in the traffic stream is established and aircraft A can be allowed to climb. Alternately, the controller may alter aircraft A's course until the aircraft can safely join a different gap in the traffic. In either case, aircraft A takes a less efficient path due to an increase in time and fuel consumed.
Another reason why it would be desirable to provide collaborative methods for modeling and planning flight routes and altitudes in the oceanic airspace is to improve airspace utilization.
Airspace spaces/slots not utilized are perishable assets. Like seats on an aircraft, once the space/slot is not used, it provides no benefit to the air traffic control service provider. Better methods for allocating spaces would reduce the numbers of unused spaces/slots, thereby conferring a benefit in the oceanic airspace because of the value of a single slot on an oceanic track.
Every day, flights crossing the vast expanses of the world's oceans enter what is called “oceanic” airspace. When flights enter oceanic airspace, two things happen: (1) the aircraft no longer directly communicates with the air traffic control (ATC) agency via VHF voice radio but uses satellite communications or HF voice/datalink (which means that the communication between the aircraft and ATC takes longer to conduct); and (2) the aircraft become separated from each other by large distances (such as up to 15 flight minutes in-trail longitudinally and 100 nm laterally). Therefore, because of the large separation standards applied in the oceanic airspace, any unused slot/space represents lost value primarily to the ATC service provider, but also to the operators.
Another reason why it would be desirable to provide collaborative methods for modeling and planning flight routes and altitudes in the oceanic airspace is to utilize shared information in a network-enabled environment to allow airlines to participate in collective flight routing decisions and optimize their individual aircraft flight profiles.
ATC service providers and aircraft operators generally cooperate to understand the weather and other conditions affecting the nation and adjacent parts of the world. However, for competitive and legal reasons, airlines generally do not share detailed flight plan information with each other. There are some efforts underway to improve information sharing, through working groups such as the Collaborative Decision Making Team and Inbound Priority Sequencing. These efforts are primarily directed at airline operators, although military and general aviation (including business jet operators) comprise a significant percentage of flights (approximately 20% or more, depending on the region of airspace being studied). These methods do not provide a basis for all aircraft operators and the air navigation service provider to optimize their operations. Instead, these activities primarily benefit the airlines (with the benefit to the air navigation service provider as a secondary benefit, rather than a primary benefit). Flights are planned individually, primarily due to existing regulatory requirements and other factors, including: (1) specific mission requirements (number of passengers, cargo, flight length, estimated winds aloft, and the like); (2) differing operational constraints in different regions; and (3) last minute aircraft configuration or payload changes that may affect aircraft weight or other operational factors for the flight.
Thus, present industry practices and methods for conducting flow planning do not provide a means to optimize cruise altitudes and system capacity for the air navigation service provider and the operators at the same time. Current methods optimize cruise altitudes for operators or system capacity for the service provider, but not both at the same time. Also, current flight planning methods optimize flight altitudes for a single aircraft operating on a single route, but not multiple aircraft on multiple flight paths.
The foregoing examples of related art and limitations associated therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.